JumpThreading: when default destination is the destination of some cases in a

switch, make sure we include the value for the cases when calculating edge
value from switch to the default destination.

rdar://12241132

llvm-svn: 163270

1 files changed, 6 insertions, 3 deletions

diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index c2306b4e9c1..ec618fad22e 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -847,9 +847,12 @@ static bool getEdgeValueLocal(Value *Val, BasicBlock *BBFrom,
     for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
          i != e; ++i) {
       ConstantRange EdgeVal(i.getCaseValue()->getValue());
-      if (DefaultCase)
-        EdgesVals = EdgesVals.difference(EdgeVal);
-      else if (i.getCaseSuccessor() == BBTo)
+      if (DefaultCase) {
+        // It is possible that the default destination is the destination of
+        // some cases. There is no need to perform difference for those cases.
+        if (i.getCaseSuccessor() != BBTo)
+          EdgesVals = EdgesVals.difference(EdgeVal);
+      } else if (i.getCaseSuccessor() == BBTo)
         EdgesVals = EdgesVals.unionWith(EdgeVal);
     }
     Result = LVILatticeVal::getRange(EdgesVals);